1. Field of the Invention
The present invention relates to agricultural sprayers, and, more particularly, to such sprayers having variable tread separation widths.
2. Description of the Related Art
Agricultural sprayers apply a liquid to a crop or the ground at a specified application rate. The liquid may be in the form of a solution or mixture, with a carrier liquid (such as water) being mixed with one or more active ingredients (such as a herbicide, fertilizer and/or a pesticide). The application rate can vary over different parts of a field through the use of precision farming techniques, such as by using GPS data to activate/deactivate boom sections of the sprayer as the sprayer traverses over the field.
Agricultural sprayers may be pulled as an implement or self-propelled, and typically include a tank, a pump, a boom assembly, and a plurality of nozzles carried by the boom assembly at spaced locations. The boom assembly typically includes a pair of wing booms, with each wing boom extending to either side of the sprayer when in an unfolded state. Each wing boom may include multiple boom sections, each with a number of spray nozzles (also sometimes referred to as spray tips). Of course, a self-propelled sprayer also includes an onboard power plant (e.g., diesel engine) providing motive force and other power such as hydraulic power, electrical power, etc.
Agricultural sprayers may generally be divided into two types or methods of application: a batch application method, and a metered application method. With a batch application method, a tank is filled with the carrier liquid, one or more active ingredients are mixed with the carrier liquid in the tank, and the solution or mixture is applied at a predetermined application rate over the field.
With a metered application method, the active ingredient(s) are mixed at a metered rate with the carrier liquid as it is transferred from a carrier tank to the sprayer nozzles. Such metering may be carried out using pumps, venturi nozzles or controllable valves. A metered application method allows the application rate to be more easily changed “on-the-fly” across a field, and avoids the need to dispose of unused spray solution at the end of a spray operation (except what may be left in the lines, pump, etc. between the tank and nozzles).
Self-propelled spaying systems have suspensions which provide a substantial crop clearance. The suspensions in many models also feature the ability to vary the tread spacing to accommodate road use requirements in a narrow width, and a wider width for field use. The width is also adjustable to accommodate the row-spacing of crops, such as corn, so that the tires can be positioned between the rows of the plants.
What is needed in the art is an agricultural sprayer with the ability to provide an adjustably narrower tracking width, and to accomplish such a width in a cost effective manner.